Slip ring assembly



J ly 31, 19 2 G. ca. STODDARD 3,047,827

SLIP RING ASSEMBLY Filed Jan. 26, 1959 INVENTOR. GLENN G. STODDARD ATTORNEY United States Patent ()fifice 3,047,827 SLIP RING AdSEMBLY Glenn G. Stoddard, Washington, Mich., assignor to Cu"- tiss-Wright Corporation, Utica Division, Utica, Mich., a corporation of Delaware Filed Jan. 26, 1959, Ser. No. 789,011 4 Claims. (Cl. 3395) The present invention relates to a slip ring assembly and particularly to a novel structure for communicating a plurality of channels of electrical information between rotating and nonrotating machine parts.

The present invention has application to those devices which contain relatively rotating parts and require the transmission of electrical current and information betweenisaid parts. In certain instances, such asordnance pieces and automated machinery, there may be a requirement for a relatively large number of'separate information channels to be conducted between such rotating parts.

Prior art slip ring assemblies for such purposes commonly employ feelers or brushes which rub against the peripheral edge of the slip ring. Where a great number of information channels are required and the slip ring assembly must be held within certain size limitations, problems arise relative to the required miniaturization of the parts. In conventional slip ring construction miniaturiza tion of the parts reduces both the mechanical and electrical reliability of the unit Particularly, the brushes become frail with reduction in size.

Therefore, in View of the foregoing state of the art, it is an object of the present invention to provide a slip ring assembly characterized by its physical and electrical ruggedness, as well as its compactness. I

It is a further object of the present invention to provide a slip ring assembly in which electrical conduction takes place through the contacting radial faces of contacting discs, such contact being further'characterized by the scrubbing action at the contacting surfaces.

A still further object of this invention is to provide an assembly for the transmission of electrical information between two relatively rotating parts which have an intermediate conductor interposed between the two rotating parts. p 7

Another object of the invention disclosed herein is to teach a slip ring assembly employing stacked sets'of conducting disc subassemblies in which the discs of each set or subassembly take the general form of planetary gearing for providing multiple paths for conducting electrical current between rotating and nonro-tating parts.

These and further objects of the present invention will become apparent from the following description and the accompanying drawings in which:

FIGURE 1 is the top plan view of a slip ring assembly constituting the preferred embodiment of the present invention;

FIGURE 2 is an elevational view partly in section, the sectional portion being taken along section lines 2-2 of FIGURE 1;

FIGURE 3 is a plan view in section taken along section Slip ring assembly 16 has an upper end member 12 and a lower end member 14 which are separated by an 2 intermediate casing 16. Casing 16 is preferably constructed of a nonconductive material, such as fiber glass reinforced plastic, for reasons which will become hereinafter apparent. The ends12, 14 and central casing 16 are held together by a series of three circumferentially spaced apart through-bolts 13. The just described components constitute the enclosure for the 'slip ring assembly and protect its inner workings from such environmental conditions as might be encountered. End pieces 12, 14 and casing 16 also form the base structure for the stationary portion of the slip ring assembly 10. Bolts 18 provide a means for attaching the slip ring assembly to the basic machinery 29 with which it is associated.

The rotating portion of the present structure comprises a shaft 22 which forms a part of the device to which the multiple channels of electrical information are to be 0on ducted. Shaft 22 is afiixed or mounted to an intermediate member 24 that is in turn carried in a bearing 26 to permit relative rotation between shaft member 22 and end cap member 12. I

The basis for the present slip ring assembly 10 resides in the concept of planetary gearing which employs concentric spaced apart sun and ring electrical conducting members having intermediate planet conducting members interposed therebetween and in contact with both the sun and ring members.

There is secured to the end piece 12 a ring gear 28 of a planetary system of gears which also includes a sun gear 30 and planet gears 32. Sun gear 30 is affixed to the intermediate shaft member 24, and ring gear 28 is held in position by the through-bolts 18.

Shaft member 24 also has associated with it radial extensions or spider arms 34, one of which is shown in FIG- URE 2. Spider arm 34 rotatably carries a planet shaft 36 that in turn carries the planet gear 32 in mesh with and interposed between sun gear 30'and ring gear 28. As will be seen inFlGURE 3, there are three planet shafts 36 disclosed as being incorporated in this the preferred embodiment. However, it is to be understood that two or four or some equally reasonable number of planet shafts might be used with success in place of three as disclosed.

The sun gear 30 and intermediate member 24 have a sun shaft 38 associated with it. Shaft 38 is afiixed to rotate with sun gearSil, member 24, and shaft 22. The sun shaft 38 and the plurality of planet shafts 36 extend for the full length of the assembly 10 and are all parallel to its longitudinal axis. The lower end of the assembly 10 adjacent the end piece 14 may be provided with a second planetary set of sun, planet, and ring gears if mechanical contingencies require such additional rigidity.

Longitudinally spaced apart relative to the ring gear 28 are a plurality of disk members 40 whichare relatively positioned to each other by means of short pieces of cylindrical tubing or spacers 42 carried on each of the throughbolts 18. Disks 40 and spacers 42are formed from nonconductive material such as phenolic plastic. The disks 40 have a circumferential strip of conductive material disposed about the inner radial face of each on its sides and forming current conducting contact rings, as indicated by the reference numeral 44. The disks 40 and the associated conductive strip 44 may be formed by any of the popular printed circuit board techniques, such as those which teach the electrodeposition of metallic conduction paths to the surfaces of insulating boards. Conversely, the pattern of the, electrical rccnducting strip 44 may be formed by an etching process which removes all of the metallic surface prelaminated on a board of plastic material except that electrical strip or conductive path which has been treated so as not to be etched away.

A terminal board 52 is secured to the lower end piece.

14 by means such as machine screws 53. Terminal board 52 provides a means for making an electrical con- Patented July 31, 1962 a nection from outside of the assembly to the series of contacting rings 44 within the assembly 10. There is shown in FIGURE 2 a series of connecting wires 54 soldered to the terminal board 52. These wires 54 are mutually independent and are each joined at their other end to separate contact rings 44. Each of the stacked series of disks 4-0 is provided with a circumferentially arranged series of holes 50 which, when the disks are assembled, form longitudinal paths for the placement of connecting wires 54. The wire 54 and those like it are soldered to the electrical conducting strip 44 of the respective disks and pass longitudinally parallel to the axis of the assembly 10 through the appropriate holes and are then connected to the external terminal board 52.

In the embodiment of the invention shown there are electrical contact rings 44 on each side or face of the disks 40 which constitute mutually independent circuits paths, Therefore, for each disk there are two circuit paths and it is thus necessary to provide twice as many holes 50 as there are disks 40. There will be two connecting wires 54 associated with each disk 40 to conduct current to each of the strips 44 on each of the two sides thereof;

Disposed concentrically about the sun shaft 38 are a plurality of sun disks 62 which are provided with keyway slots to engagethe ribs 63 provided on shaft 38 so that they turn conjointly. The disks 62 are of a construction similar to the disks 40 and are formed from a plastic material so as to be nonconductive. There is provided along the radial edge of each side of the disc 62 a metallic conducting ring or surface 65. This also may be formed by any of the common printed circuit board techniques. The disk 62 is provided with a series of circumferentially spaced apart holes 64 through which connecting wires such as 66 are to be passed to connect the electrical contact surfaces 65 at the edge of disk 62 to an external terminal board 68 that is carried by the rotatable shaft 22 and intermediate member 24. The terminal board 68 is held in position by a nut 69 threaded to the shaft 22.

Holes 64 and wires 66 are provided for each of the conducting rings 65 of the disks 62, which means that there are two holes 64 and two wires 66 for each disk 62. Like the holes 50 in ring 40, holes 64 of the series of parallel disks 62 are longitudinally aligned for easy placement of wires 66.

A series of planet disks 70 provides means for connecting the electrical contact surfaces 44 and 65 of respective disks 40 and 62 together. The planet contact disks 70 are keyed to the planet shaft 36 in a manner similar to the keying of the sun disk 62 to its shaft 38. Planet disks 70 each have a single contact surface 72 which is a metallic strip about the radial edge of one side for the conduction of electrical current and information. As shown in the drawing, the planet disk 70 is positioned'in overlapping engagement with the concentrically disposed disks 40 and 62 so that an electrical path is formed through metallic surface 72 between the contacting surface 44 of disk 46 and the metallic facing 65 about the edge of sun disks 62.

The relative position of the planet disks 70 to the position of the disk 4t) is maintained by a series of small thrust springs 74 which urge the conducting faces into contact. In the arrangement disclosed in the drawing the sun disks 62 are held in firm contact between pairs of spring-pressed planet disks 70.

In the foregoing description, disks 40 were described as having conducting surfaces 44 on either of their faces. Likewise the sun contact disks 62 have contact electrical conducting bands or strips 65 around their radial faces on both their sides. With this situation there are separate planet contact disks for each of the conducting faces, inasmuch as it is necessary to provide thrust spring 74 to keep the faces in firm contact. In the just described arrangement, that is, where the concentrically disposed disks have conducting surfaces on both faces, two channels of electrical information may be transmitted for each planetary set of disks.

The foregoing structure permits the mere selection of the appropriate number of planetary conducting sets corresponding to the number of channels of electrical information which must be conducted between the two relatively rotating parts. In principle, assembly 10 may have any reasonable longitudinal length thatis necessary to accommodate the specified number of planetary slip ring sets required to conduct the desired number of information channels. g

It will be noted that the contacting faces have a substantially large touching area and thatthe contact is maintained by a scrubbing action when there is relative movement between the parts.

The foregoing constitutes the preferred form of the present invention. It is to be understood that other modifications and embodiments may occur to those with ordinary skill in the art which will come within the scope and spirit of this disclosure as defined by the following claims.

I claim:

1. A slip ring assembly for conducting electrical current between relatively rotatable members, and comprising: an annular member having a circular member disposed in concentric spaced relation thereto and each having flat side faces and a current conducting surface provided on at least one side face of each thereof, a current conducting disk disposed in planetary relation between said annular and'circular members and in engagement with the side faces thereof including said current conducting surfaces, and drive means operatively connected to one of said annular and circular members for rotation thereof. 7

2. The slip ring assembly of claim 1 including planetary gear means operatively connected to said circular, annular and planetary members for relative rotation thereof.

3. The slip ring assembly of claim 1 wherein said annular and circular members are disposed in coplanar relation and said conducting surface is provided on coplanar face of each thereof.

4. A slip ring assembly, comprising: multiple pairs of coplanar concentrically spaced disks disposed in coaxial spaced relation, each of said disks having a current conducting ring provided on each side face thereof, planetary disposed disks provided between said pairs of coaxial spaced disks in overlapping relation to said concentrically spaced disks and having a current conducting ring provided on at least one side face thereof and disposed for engagement with the current conducting rings of one of said pairs of coaxially spaced disks, drive means interconnected to one each of said concentrically spaced disks for relative rotation thereof, and planetary gear means operatively connected between said drive means and said planetary disposed disks for planetary rotation thereof and scrubbing contact engagement between the current conducting rings thereof and the rings of said concentrically spaced disks.

References Cited in the file of this patent UNITED STATES PATENTS 2,274,514 Willsey Feb. 24, 1942 2,319,443 Corte May 18, 1943- 2,409,600 ,Trautschold Oct. 15, 1946 2,467,758 Lindenblad Apr. 19, 1949 2,932,810 Novak Apr. 12, 1960 

